Growing wine grapes in non-traditional regions like Minnesota on a commercial scale is a relatively new endeavor because the region's mid-continental climate yields exceptionally cold winters that create challenges for the emerging wine industry. At the same time, the cold climate in Minnesota creates opportunities for the production of wines with increased acidity, which can result in a more complex mouthfeel, and be particularly useful in balancing fortified wines with relatively high alcohol content.
Currently, less than 100 wineries exist in Minnesota, extending from southern Minnesota to just south of the Canadian border. Many of these wineries produce non-grape wines from honey, rhubarb, raspberries, and the other fruit. However, several Minnesota wineries are currently managing substantial vineyard tracts. A few wineries have even received awards for wines produced by these vineyards at top international wine competitions.
Despite some success, grape growing in Minnesota is fraught with difficulties. Most European grape varieties that are grown in Minnesota, and even many “French-American hybrid” wine varieties, require protection if they are to survive the frigid winter temperatures—especially in northern Minnesota. This is usually done by removing vines from the trellises and bending them to the ground in early November, then covering the vine with soil or straw.
Although covering vines effectively insulates them from cold winter temperatures, there are a number of problems that make this practice less than satisfactory. Of primary concern is the greatly increased labor cost, which is generally prohibitive and makes it quite difficult for cold-climate vineyards to operate profitably. However, logistical challenges exist as well. For example, the trunks of the vine may break due to the fact that they become less pliable as they grow larger in diameter. If the vine does not break, fungi and bacteria may infiltrate the vine through small “stress cracks” in the trunk, causing disease. Rodents may also feed on the trunks and canes as they lay on the ground during the winter, further injuring the vine. If the vine survives the winter, great care must be taken to avoid damaging the buds when the vines are uncovered during the spring. Accordingly, for grapevines to be of high commercial value to vineyards in northern regions, it is nearly essential for varieties to be hardy enough to remain on the trellises throughout the winter months without removal and winter covering.
Fortunately, there exist good sources of tolerance to cold hardiness for breeding purposes, i.e. Vitis riparia and Vitis labrusca. These hardy grapes have a flavor that is acceptable in table wines. However, they are generally too high in acid and too unproductive to use on their own.
Some of the hardiest known wine grape varieties, ‘Sabrevois’ (not patented) (ES 2-1-9), and ‘Frontenac’ (not patented) (MN 1047), have demonstrated hardiness to at least −35 degrees F. (about −37.2 degrees C.) in central Minnesota. The ‘Chisago’ grape (U.S. Plant Pat. No. 19,246) and ‘Nokomis’ grape (U.S. Plant Pat. No. 23,376) have been shown to be winter hardy to about −40 degrees F. (about −40 degress C.). In central Minnesota, the present variety has proven that it is at least as winter hardy as these known varieties. The present variety also presents a wide variety of additional distinguishing characteristics including resistance to disease and pests, vigor, productivity, size of fruit, size of grape clusters, coloration, and flavor, hereinafter set forth in detail. Most notably, the berries of ‘Franconia’ are larger than both the ‘Chisago’ and ‘Nokomis’ grapes. However, the ‘Franconia’ generally contains less berries per cluster than both the ‘Chisago’ and ‘Nokomis’ cultivars. ‘Franconia’ berries along the transverse axis are 0.6 inch (15.24 mm) to 0.82 inch (about 21 mm). These berry dimensions are larger than both the ‘Chisago’ grape and ‘Nokomis’ grape. The dimension of the berries along the longitudinal axis of the ‘Chisago’ and ‘Nokomis’ grapes are generally smaller at 0.4375 inch (about 11 mm) to 0.5 inch (12.7 mm) along the longitudinal axis and 0.5 inch (12.7 mm) to 0.75 inch (about 19 mm) along the transverse axis. The weight of ‘Franconia’ berries were observed to be 0.08 ounces (about 2.3 grams) to 0.19 ounces (about 5.4 grams). By comparison, the weight of the ‘Chisago’ and ‘Nokomis’ berries are known to be slightly smaller at 0.07 ounces (about 2 grams) to 0.14 ounces (about 4 grams). The ‘Franconia’ vines are generally less susceptible to powdery mildew and downy mildew than Nokomis, and similar in general disease resistance to Chisago.